>>1824378>>1824381This is an interesting comparison. Let's look in detail at this. It's notable how relatively little infrastructure goes pretty far: it's just three subway lines, two of which share the same tracks for a while and then branch off. Then you have the S-Bahn trains, which usually run on existing mainline railways. And then there's a handful of tram lines.
Baltimore could improve transit quite significantly with relatively low effort if this concept is applied: First, turn mainline railways into S-Bahn type services that don't go as far out as MARC commuter rail, and have frequency of at least 15 minutes. Start off with the existing service, the Penn line running roughly east-west (orange). There you have a complementary service to the subway line.
There's another railway line going from Penn Station to the north then east and south, roughly circling the city, this could be another potential S-Bahn "semi-circle" service (brown).
Since the Camden line ends at another station, a tram-train service could be established to around St Denis which could go further into the city on the existing LRT tracks (purple)
All of this would require zero miles of additional rail line, and would go a long way to a semblance of a decent transit system. DMUs could be used at first on the lines that aren't electrified,
Now a next step, the subway could be extended on the eastern end, branching out with one line continuing north along Broadway and meeting the Penn S-Bahn line and the new semi-circle line; and eastwards along Fayette to the point where the Penn and the semi-circle line meet. That area could be redeveloped around the rail lines, as it will be a significant transit center.
Now add to that a few LRT lines to fill up the most important gaps (thin blue lines as example)
All in all this isn't peanuts, but it wouldn't be entirely unrealistic either, proceeding in gradual steps that each would make transit more attractive.
